Quantitative and qualitative changes in field pea (Pisum sativum L.) from seed formation to maturity | Kvantitativne i kvalitativne promene proteinskog graška (Pisum sativum L.) od formiranja do žetvene zrelosti semena

Field trials were established at experimental fields Rimski Šančevi, Institute of Fieldand Vegetable Crops Novi Sad, with the aim to determine the quantitative andqualitative changes in field pea (Pisum sativum L.) from seed formation stage to harveststage. Trials were carried out under field conditions during three growing seasons:2010, 2011, and 2012. Field trials were set as a randomized block design with fourreplications on randomly distributed plots. Size of the elementary plot was 18 m² (6 x 3m) using inter-row spacing of 20 cm.The trial included ten most widespread field pea cultivars in Serbia: NS Junior, Jantar,Timo, Trezor, Javor, Dukat, Jezero, Kristal, Angela and Partner. The tested cultivarswere distributed into five groups, each group consisting of two cultivars. The groupswere formed according to stem grow habit (indeterminate and determinate), leaf type(conventional and afila type), vegetation period, seed size, and plant use (mixed foragegrain or grain only).Linear increase in seed weight was observed from the first until the third harvestingperiod, amounting to 7.55 g. Daily increase in seed mass was 0.5 - 0.6 g per plant inthis period. Seed mass increase continued until the fourth harvesting period, withsignificantly lower intensity. During the fourth harvesting period, average seed masswas 8.42 g, with daily increase of about 0.2 g. During the fifth and the sixth harvestingperiod, average seed mass was 8.54 g and 8.40 g, respectively.Seed moisture content was the highest in the first harvesting period, on average 64.6%. Seed moisture content decreased exponentially until the last harvesting period,amounting to 12.3% on average. Meanwhile, the intensity of decrease in seed moisturecontent significantly varied between harvesting periods. The lowest decrease of 6.3%occurred between the first and the second harvesting period, and 8.2% in the fifth andthe sixth harvesting period. Average daily loss of field pea seed moisture was 1.6%, i.e.2.0% in the abovementioned intervals. Intensity of seed moisture loss between thesecond and the third harvesting period (10.1%) was very similar to that of the fourthand the fifth (10.2%). Daily loss of seed moisture amounted to 2.5% during theseintervals. The highest decrease of seed moisture content (17.5%) occurred between thethird and the fourth harvesting period. Daily loss of seed moisture was 4.4% in thatinterval.The highest average seed yield was obtained from the medium early cultivars withdeterminate stem growth, regardless of the leaf type. Average seed yield obtained fromthe cultivar Kristal (afila type) was 5078 kg/ha, whereas seed yield obtained from theconventional-leaf type cultivars Javor and Dukat was 4989 kg/ha and 4846 kg/ha,respectively. The lowest seed yield was obtained from the late maturity cultivars withindeterminate stem growth intended for mixed use (forage-grain), namely NS Junior(2717 kg/ha) and Jantar (2690 kg/ha).Seed germination energy obtained in the trial increased during the latter harvestingperiods, from 39.2% (the first period) to 77.7% (the sixth period). However, intensiveincrease in germination energy was observed until the fourth harvesting period, i.e.below the seed moisture content of 30%.Average seed germination also increased gradually, from 53.5% in the first harvestingperiod to 93.7% in the last. Similarly to the germination energy, the highest increase ingermination occurred until the fourth harvesting period, at seed moisture content ofabout 30%. However, mechanical pea harvesting is impossible at this level of seedmoisture. Seed germination increased between the fourth and the fifth harvesting periodby about 10%, at 20% seed moisture content. This period can therefore berecommended as the optimum harvesting period of cultivars with determinate stemgrowth. Optimum harvesting period for late maturity cultivars with indeterminate stemgrowth is halfway between the fifth and the sixth harvesting period, at seed moisturecontent of about 15%.